Re: recent ccache trouble?

I didn't try logging on NetBSD, but on the mac, at the suggestion of a
colleague, I added:
CCACHE_COMPILERCHECK?= %compiler% -v
.export CCACHE_COMPILERCHECK
That restores the expected behavior; I see 17/1 direct/preprocessed
hits.
The ccache man page warns about this; by default the compiler is
identified by the combination of mtime and size, and the mtime changes
every run.
So I wonder why this is a problem now. It seems mk/compiler/ccache.mk
sets CCACHE_HASHCC, but that variable is not mentioned any more in the
3.1.4 man page.
So it seems we need to change ccache.mk to set CCACHE_COMPILERCHECK
(additionally), so it works with either version of ccache.